DEAR DR. BLONZ: Is there truth to the "raw foods" movement's claim that cooking kills the natural enzymes in foods, including vegetables, and that this removes the vital nature of the food and poisons our bodies?
DEAR J.C.: Raw foods contain enzymes that play a part in the metabolism of the plant while it is alive, and this includes the creation of the seed. Inside a viable seed, enzymes play a role in nourishing the growth of a new plant. Heat can destroy these plant enzymes, but -- and this is the key -- these enzymes are there for the plant, not for us.
The body makes its own enzymes to digest the foods we eat. Our digestive process tends to destroy any enzymes already present in our food. They tend to be proteins in nature and get treated like other proteins we might consume. The acidic environment of the stomach denatures the enzyme, then our own digestive enzymes begin the job of breaking them down to their amino acid parts in preparation for absorption.
Cooking can make certain foods easier to digest, and it can even make certain plant nutrients more bioavailable for our bodies. Appropriate cooking will "kill" anything that is alive in a food, but eating food prepared in this manner does not poison our body. Overcooking (excess heat) can destroy much of the nutritive value of a food; it can, if taken to an extreme, create mutagenic and carcinogenic substances -- but that is not what we are talking about here.
There is nothing wrong with eating fresh, wholesome plant foods that have not been cooked, but do it because you like the taste -- not because you fear that cooking creates poisons.
DEAR DR. BLONZ: I have a friend who is lactose-intolerant, and I was wondering if her allergy to milk means that she should not have butter.
DEAR M.A.: Lactose intolerance is not the same as an allergy to milk. This type of intolerance occurs when the body does not produce sufficient amounts of an enzyme (lactase) to digest a naturally occurring carbohydrate (lactose) present in many dairy products. When a lactose-intolerant individual consumes more lactose than her body can handle, she can experience symptoms such as stomachache, bloating, gas or diarrhea. These individuals usually have no problem with butter as it contains little, if any, lactose.
A milk allergy occurs when there is a specific sensitivity to milk protein. This condition should be confirmed through testing by an allergist. When an individual with a milk allergy eats a food containing milk protein, he can -- depending on his level of sensitivity -- experience symptoms ranging from sneezing, runny nose, asthma, skin rashes, nausea, diarrhea, swelling, headache, or even a life-threatening drop in blood pressure. Butter contains a small amount of protein; it, along with all other dairy products, should be considered off-limits for an individual with a milk allergy.
Kensington resident Ed Blonz has a Ph.D. in nutrition from UC Davis. Email him at email@example.com.